Cadmium (Cd) is a threatening heavy metal pollutant to aquatic organisms. The hepatopancreas plays a crucial role in combating environmental stress and enhancing the immune defense of aquatic species. The exact mechanism behind the damage induced by Cadmium in the hepatopancreas of Fenneropenaeus merguiensis is unclear. Thus, this study aimed to elucidate the potential mechanisms of Cadmium's impact on the hepatopancreas of F. merguiensis through physiological, histological, and transcriptomic analyses. After 72 h of F. merguiensis exposure to the 0.5 mg/L concentration of cadmium results in the reduction of superoxide dismutase and catalase activities, coupled with an increase in hydrogen peroxide and malondialdehyde levels, which leads to damage in both the gills and hepatopancreas. This causes severe histological changes in the gills and hepatopancreas of F. merguiensis , characterized by irregularities in the gill filaments and ruptures in the basal membrane of the hepatopancreas. Comparative transcriptomic analysis of F. merguiensis revealed the upregulation of several genes associated with pathways related to metabolism (ko01100), antigen processing and presentation (ko04612), and cell apoptosis (ko04215), indicating adaptive response mechanisms to Cadmium exposure. Transcriptomic analysis also showed that Cadmium exposure induced the expression of genes related to detoxification and apoptosis, such as heat shock proteins, metallothionein, and Caspase-3 , suggesting adverse effects on the normal physiological functions of F. merguiensis . Our study provides comprehensive insights into the toxicological mechanisms and impacts of Cadmium on F. merguiensis.
Zou Peizhuo,Yang Qian,Wang Hailiang,Xie Guosi,Cao Zhi,Chen Xing,Gao Wen,Huang Jie
Acute hepatopancreatic necrosis disease (AHPND) is one of the most significant bacterial diseases in global shrimp culture, causing severe economic losses. In the present study, we carried out in vitro antimicrobial tests to investigate the disinfection efficacy of 14 common disinfectants toward different AHPND-causing Vibrio spp., including eight isolates of V. parahaemolyticus , four isolates of V. campbellii , and one isolate of V. owensii . Polyhexamethylene biguanidine hydrochloride (PHMB) was revealed to possess the strongest inhibitory activity. Through analyzing and evaluating the results of antimicrobial tests and acute toxicity test, we selected PHMB and hydrogen peroxide (H 2 O 2 ) for further clinical protection test. Clinical manifestations indicated that both PHMB (2 mg/L and 4 mg/L) and H 2 O 2 (12 mg/L) could effectively protect juvenile Penaeus vannamei from the infection of V. parahaemolyticus isolate Vp 362 at 10 6 CFU/ml, and the survival rate was over 80%. When the bacterial concentration was reduced to 10 5 CFU/ml, 10 4 CFU/ml, and 10 3 CFU/ml, the survival rate after treated by 1 mg/L PHMB was 64.44%, 93.33%, and 100%, respectively. According to the results, PHMB and H 2 O 2 showed a lower toxicity while a better protection activity, particularly against a lower concentration of the pathogens. Therefore, these two disinfectants are proved to be promising disinfectants that can be applied to prevent and control AHPND in shrimp culture. Moreover, the methods of this study also provided valuable information for the prevention of other important bacterial diseases and suggested a reliable means for screening potential drugs in aquaculture.
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